diff options
| -rw-r--r-- | libbb/printf.c | 131 |
1 files changed, 27 insertions, 104 deletions
diff --git a/libbb/printf.c b/libbb/printf.c index e61723242..7eb60a91e 100644 --- a/libbb/printf.c +++ b/libbb/printf.c @@ -4,20 +4,7 @@ * * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org> * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - * + * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ /* Mar 12, 2003 Manuel Novoa III @@ -33,102 +20,23 @@ * failure. That would allow us to defer error checking until applet * exit. Unfortunately, there is no standard way of setting a streams * error indicator... even though we can clear it with clearerr(). + */ + +/* Mar 22, 2006 Rich Felker III * - * Therefore, we have to resort to implementation dependent code. Feel - * free to send patches for stdio implementations where the following - * fails. - * - * NOTE: None of this is thread safe. As busybox is a non-threaded app, - * that isn't currently an issue. + * Actually there is a portable way to set the error indicator. See below. + * It is not thread-safe as written due to a race condition with file + * descriptors but since BB is not threaded that does not matter. It can be + * made thread-safe at the expense of slightly more code, if this is ever + * needed in the future. */ #include <stdio.h> #include <stdarg.h> +#include <unistd.h> +#include <errno.h> #include "libbb.h" -#if defined(__UCLIBC__) - -# if defined(__FLAG_ERROR) -/* Using my newer stdio implementation. Unlocked macros are: - * #define __CLEARERR(stream) \ - ((stream)->modeflags &= ~(__FLAG_EOF|__FLAG_ERROR), (void)0) - * #define __FEOF(stream) ((stream)->modeflags & __FLAG_EOF) - * #define __FERROR(stream) ((stream)->modeflags & __FLAG_ERROR) - */ -# if defined(__MASK_READING) -# define SET_FERROR_UNLOCKED(S) ((S)->__modeflags |= __FLAG_ERROR) -# else -# define SET_FERROR_UNLOCKED(S) ((S)->modeflags |= __FLAG_ERROR) -# endif - -# elif defined(__MODE_ERR) -/* Using either the original stdio implementation (from dev86) or - * my original stdio rewrite. Macros were: - * #define ferror(fp) (((fp)->mode&__MODE_ERR) != 0) - * #define feof(fp) (((fp)->mode&__MODE_EOF) != 0) - * #define clearerr(fp) ((fp)->mode &= ~(__MODE_EOF|__MODE_ERR),0) - */ -#define SET_FERROR_UNLOCKED(S) ((S)->mode |= __MODE_ERR) - -# else -# error unknown uClibc stdio implemenation! -# endif - -#elif defined(__NEWLIB_H__) -/* I honestly don't know if there are different versions of stdio in - * newlibs history. Anyway, here's what's current. - * #define __sfeof(p) (((p)->_flags & __SEOF) != 0) - * #define __sferror(p) (((p)->_flags & __SERR) != 0) - * #define __sclearerr(p) ((void)((p)->_flags &= ~(__SERR|__SEOF))) - */ -# define SET_FERROR_UNLOCKED(S) ((S)->_flags |= __SERR) - -#elif defined(__GLIBC__) - -# if defined(_STDIO_USES_IOSTREAM) -/* Apparently using the newer libio implementation, with associated defines: - * #define _IO_feof_unlocked(__fp) (((__fp)->_flags & _IO_EOF_SEEN) != 0) - * #define _IO_ferror_unlocked(__fp) (((__fp)->_flags & _IO_ERR_SEEN) != 0) - */ -# define SET_FERROR_UNLOCKED(S) ((S)->_flags |= _IO_ERR_SEEN) - -# else -/* Assume the older version of glibc which used a bitfield entry - * as a stream error flag. The associated defines were: - * #define __clearerr(stream) ((stream)->__error = (stream)->__eof = 0) - * #define feof_unlocked(stream) ((stream)->__eof != 0) - * #define ferror_unlocked(stream) ((stream)->__error != 0) - */ -# define SET_FERROR_UNLOCKED(S) ((S)->__error = 1) - -# endif - -#elif defined(__dietlibc__) -/* - * WARNING!!! dietlibc is quite buggy. WARNING!!! - * - * Some example bugs as of March 12, 2003... - * 1) fputc() doesn't set the error indicator on failure. - * 2) freopen() doesn't maintain the same stream object, contrary to - * standards. This makes it useless in its primary role of - * reassociating stdin/stdout/stderr. - * 3) printf() often fails to correctly format output when conversions - * involve padding. It is also practically useless for floating - * point output. - * - * But, if you're determined to use it anyway, (as of the current version) - * you can extract the information you need from dietstdio.h. See the - * other library implementations for examples. - */ -# error dietlibc is currently not supported. Please see the commented source. - -#else /* some other lib */ -/* Please see the comments for the above supported libraries for examples - * of what is required to support your stdio implementation. - */ -# error Your stdio library is currently not supported. Please see the commented source. -#endif - #ifdef L_bb_vfprintf extern int bb_vfprintf(FILE * __restrict stream, const char * __restrict format, @@ -137,7 +45,22 @@ extern int bb_vfprintf(FILE * __restrict stream, int rv; if ((rv = vfprintf(stream, format, arg)) < 0) { - SET_FERROR_UNLOCKED(stream); + /* The following sequence portably sets the error flag for + * stream on any remotely POSIX-compliant implementation. */ + + int errno_save = errno; + int fd = fileno(stream); + int tmp = dup(fd); + + fflush(stream); + close(fd); + /* Force an attempted write to nonexistant fd => EBADF */ + fputc(0, stream); + fflush(stream); + /* Restore the stream's original fd */ + dup2(tmp, fd); + close(tmp); + errno = errno_save; } return rv; |